EXCHANGE RATE! * THERMAL THAT HAS LINKED LAUNCHES DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an apparatus and method for maximizing heat transfer in fin enhancements of both upstream and downstream A Heat Exchanger Flap Background of the Invention The finned heat exchanger coil assemblies are widely used in a number of applications in fields such as air conditioning and refrigeration. A finned heat exchanger coil assembly generally includes a plurality of parallel spaced tubes through which a thermal transfer fluid such as water or coolant flows. A second heat transfer fluid, usually air, is directed through the tubes. A plurality of fins is usually employed to improve the thermal transfer capabilities of the heat exchanger coil assembly. Each fin is a thin metal plate, made of copper or aluminum, which may or may not include a hydrophilic coating. Each fin includes a plurality of openings for receiving the spaced-apart parallel tubes, so that the tubes generally pass through the plurality of fins at right angles to the fins. The fins are arranged in a parallel, closely spaced relationship along the tubes to form multiple paths for air or other heat transfer fluid to flow through the fins and around the tubes. Frequently the fin includes one or more improvements to improve the thermal transfer efficiency. For example, many heat exchanger fins of the above branch include a uniform improvement, such as a corrugated or sinusoidal-like configuration when viewed in cross section. In addition, or instead of, uniform improvement, the heat exchanger fins may also include improvements such as lancets or blinds. These improvements are formed from a line of material (the plane of the fin material from which all fin features are formed). Usually, these improvements are symmetric, with reference to any point along the air path passing over the fin so that the improved fins include both upstream and downstream improvements. Unfortunately, upstream and downstream lancets are often formed at the same angle with respect to the material line. This results in downstream lancets that are in the wake of the upstream lancets, inhibiting effective thermal transfer between the downstream lancets and the air. Additionally, the overlapping blinds have the same problem, that is, the thermal transfer operation of the blinds downstream is adversely affected by the blinds upstream. Thus, there is a need to provide an improvement that maximizes the effective thermal transfer of both upstream and downstream lancets. COMPENDIUM OF THE INVENTION In accordance with one aspect of the present invention, a heat exchanger coil assembly is provided. The assembly comprises a plurality of fins disposed substantially in parallel with an average air flow direction, so that air can flow between adjacent fins, each fin having a plurality of cylindrical sleeves and a corrugated configuration comprising at least two corrugations, each corrugation including a first lancet and a second lancet downstream of the first lancet, wherein the first lancet is inclined at a first angle with respect to the average air flow direction and the second lancet is inclined at a second angle with respect to to the direction of medium air flow.
the first angle being different from the second angle so that when the air flow passes over the fin, a wake of the first lancet will not affect the second lancet, and a plurality of heat transfer tubes disposed substantially perpendicular to the plurality of fins, each tube passing through the cylindrical sleeves in the plurality of fins. In accordance with another aspect of the present invention, there is provided a finned heat exchanger coil assembly, wherein the heat transfer occurs between a first fluid flowing through a plurality of heat transfer tubes with separate fins and a second fluid that flows out of the tubes. Each fin has a corrugated configuration with at least two corrugations, each corrugation having a first lancet and a second lancet downstream of the first lancet, wherein the first lancet is inclined at a first angle with respect to an average air flow direction and the second lancet is inclined at a second angle with respect to the direction of the mean air flow, wherein the first angle is different from the second angle so that when the air flow passes over the fin, a wake of the first lancet It will not affect the second lancet. In accordance with a further aspect of the present invention, there is provided a finned heat exchanger coil assembly, wherein heat transfer occurs between a first fluid flowing through a plurality of heat transfer tubes with spaced fins and a second fluid that flows out of the tubes. Each fin comprises at least two corrugations, each corrugation having a first lancet on one side upstream of the corrugation and a second lancet on a downstream side of the corrugation, wherein the first lancet forms an angle of between 5 and 15 degrees with respect to an average air flow direction, and wherein the second lancet is parallel to the mean air flow direction, so that a wake of the first lancet will not impact the second lancet. Additional objects and advantages of the invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. The objects and advantages of the invention will be realized and achieved by means of the elements and combinations particularly noted in the appended claims. It should be understood that both the above general description and the following detailed description are examples and explanatory only and not restrictive of the invention, as claimed. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and together with the description, serve to explain the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a heat exchanger coil assembly in accordance with the present invention; Figure 2A is a top view of a heat exchanger fin in accordance with the present invention; Figure 2B is a side view of a portion of the heat exchange fin of Figure 2A taken along line B-B; Figure 3 is a side view of an exemplary heat exchanger fin designed in accordance with the present invention; Figure 4 is a side view of streamlines of air flow moving through a heat exchanger fin (the air flow is from left to right) in accordance with the present invention; and Figure 5 is a side view of streamlines of air flow moving through a conventional heat exchanger fin. DESCRIPTION OF THE MODALITIES Reference will now be made in detail to the present embodiment of the invention, an example of which is illustrated in the accompanying drawings. Whenever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts. In accordance with the present invention, there is provided a finned heat exchanger coil assembly having a uniform improvement such as a sinusoidal shape (eg, a configuration formed by the intersection of two circular arcs attached at a tangency point). ) or a corrugated form. Preferably, fin improvements are corrugated in shape. Each corrugation includes an ascending ramp and a descending ramp, wherein each ascending ramp and each descending ramp includes at least one lancet, and wherein each lancet on a descending ramp is positioned so that it is not in the wake of an upstream lancet. Of the same.
The heat exchanger coil assembly generally comprises a plurality of fins, a plurality of tubes passing through the apertures of the fins, and end plates positioned on either side of the plurality of fins.
In accordance with the present invention, the heat exchanger coil assembly includes a plurality of tubes. As is modalized herein and shown in Figure 1, a plurality of tubes 20 are provided in the heat exchanger coil assembly. The hollow tubes 20 extend along the length of the assembly 10 and are connected to each other at their ends by tube portions 20a bent into a U-shape. The tubes are tied together and provide a bundle of heat transfer tubes in the form of serpentine. The tubes 20 are connected to a thermal transfer fluid inlet 14 and thermal transfer fluid outlet 16, as shown in Figure 1. The thermal transfer fluid inlet 14 and the thermal transfer fluid outlet 16 may be placed, for example, in the lower portion of the assembly, or in a side portion of the assembly 10. The number of tubes and their arrangement may vary depending on the requirements of a specific application. The tubes are typically made of copper, however, other appropriate materials can also be used. The tubes typically have a round or oval cross section, however, other suitable shapes may be used. A first heat transfer fluid flows through the tubes 20, and a second heat transfer fluid flows over the tubes 20. The tubes 20 provide heat transfer between the first and second heat transfer fluids. Generally, the first thermal transfer fluid is water or a refrigerant. However, any suitable thermal transfer fluid can be used. The second heat transfer fluid is usually air, which is being heated or cooled by the thermal transfer between the first fluid in the tubes 20 and fins 30 and the air flowing over the tubes 20. Other suitable heat transfer fluids can be used . In the presently preferred embodiment, 2-12 rows of tubes will be provided to the heat exchanger of the present invention, with preferred embodiments including 6, 8 or 10 rows, and the most preferred embodiment including 6 rows. In accordance with the present invention, the heat exchanger coil assembly 10 is provided with a plurality of fins 30. The plurality of fins 30 is employed to improve the thermal transfer capabilities of the heat exchanger coil assembly. Each fin 30 is a thin metal plate having high thermal conductivity, preferably made of copper or aluminum. Each flap 30 may or may not include a hydrophilic coating. Each flap 30 includes a plurality of cylindrical sleeve openings 31 for receiving the spaced-apart parallel tubes 20, so that the tubes 20 generally pass through the plurality of fins 30 at right angles to the fins 30 as seen in FIG. Figure 1. The fins 30 are preferably arranged in a parallel, closely spaced relationship along the tubes 20 to form multiple paths for the air or other heat transfer fluid flowing between the fins 30 and through the tubes 20. The end plates 12 are placed on either side of the fins arranged. The fins of μ? only heat exchanger have the same dimensions. In general, depending on the intended use of the heat exchanger, the dimensions of the fins may vary from less than 2.54 cm (1") to 101.60 cm (40") in width and up to 121.92 cm (48") in height. 30 has improvements without lancets or uniforms generally designated by the reference number 32. These uniform improvements 32 are preferably corrugations 33 of fin 30 and, as shown in Figure 2B, the corrugations 33 may be slightly flattened or slightly rounded as which would be the theoretical apex of the "V" shape.
Alternatively, other uniform magnifications such as a sinusoidal-like shape can be used. As is modalized herein and shown in Figure 2B, the corrugated configuration 32 is extruded from the material line and forms at least two corrugations 33- Each corrugation 33 is generally in the form of an inverted, slightly flattened "V" and includes an ascending ramp 34 and a descending ramp 36. Each "V" shaped corrugation has an angle T formed between an imaginary horizontal line drawn through the larger portion of the inverted "V" and a leg or ramp of "V". "V", as shown in Figure 2B.A preferred scale for the angle T is between 5 and 17 degrees, with 17 degrees being the most preferred angle.These corrugations 33 preferably have a width W, from the base of the ramp ramp 34 ascending to the base of the descending ramp 36, approximately 1.27 cm (1/2"), as shown in Figure 2B. Within each corrugation 33, the descending ramp 36 is downstream of the ascending ramp 34. As used herein, "downstream" is intended to reflect the position of one element with respect to another element with respect to the direction of the mean air flow. The average air flow direction is shown in Figures 2B and 4 as moving from left to right.
Each ramp 34, 36 of each corrugation 33 includes a lancet. In this manner, each ascending ramp 34 includes a lancet 38 and each descending ramp 36 includes a lancet 40. As used herein, "lancets" can be differentiated from "blinds" in that the louvers are lancets that are aligned thereto. angle one behind the other similar to individual blinds of a window curtain. The lancets do not need to be aligned as described above, but when they are, they are called blinds. In addition to the lancets 38 and 40, which are cut from the corrugated form 32 of the fin 30, each corrugation 33 also includes a crest and a tundish. Both the crest and the trough can act as lancets. In this way, even when not primarily intended to function as lancets, the crest forms a convexly rounded lance 42 and the trough forms a concavely rounded lancet 44. The lancets 38 r 40 serve to mix stratified layers by air temperature in the air flow that moves through the fin 30 and act as boundary layer restarts. Each time the air flow encounters a lancet 38, 40, a layer of stagnant air adjacent the fin 30 begins to thicken, increasing the thermal resistance at the fin surface across the length of the lancet, increasing in this way the insulating effect on the fin surface of that lancet. By continuously restarting the limit layer, the lancets increase the amount of heat transfer between the air and the fin 30 by minimizing the thickness of the limit layer over the length of the lancet. The longer the air flow continues without finding a lancet, the thicker the boundary layer becomes and the thermal transfer between the fin and the air flow is less efficient. It is preferable that the upstream and downstream lancets 38, 40 have the same length L, as shown in Figure 2B. Alternatively, they may have different lengths. The preferred size of the lancets is 1/3 the size of the ascending ramp 34 or descending ramp 36 of the corrugations 33. However, it is intended that lancets of different sizes can be used, with shorter lancets being preferred. Smaller lancets and more lancets are preferred because they cause the boundary layer to restart more frequently. Restarting the boundary layer reduces the thermal resistance at the fin surface and increases the total convective heat transfer from the fin surface. The lancets 3840 should be oriented with respect to the air flow over the fin 30 in order to cause the desired mixing of the air layers stratified in temperature. In addition, the lancets 38, 40 must be positioned / oriented so that the downstream lancet of a determined corrugation 33, for example the lancet 40, is not in the wake path of the upstream lancet in that particular corrugation. , for example the lancet 38. If the lancet of downstream, lancet 40, is in the wake of the current lancet arrives lancet 38r the lancet of downstream can not act as a restart of limit layer. Therefore, the limit layer will continue to thicken as the air flow moves over the downstream lancet, reducing the effective amount of heat transfer between the air flow and the fin 30. Similarly, between the corrugations 33, the downstream lancet (the lancet upstream of the next corrugation 33a) should not be placed so that it is in the wake of the upstream lancet (the lancet downstream of the corrugation 33 above). As used herein, the term "wake" refers to the disturbed portion of a volume flow downstream from a body submerged in the flow. For example, in the present invention, the disturbed portion of a volume downstream air flow from a lancet submerged in the air flow would be referred to as the wake. Within each corrugation 33, the downstream lancet 40 is positioned so that it is not in the wake of the upstream lancet 38. This is achieved by providing the upstream lancet 38 and the downstream lancet 40 at different angles with respect to the corrugated form 32, so that one lancet is inclined with respect to the other lancet. By tilting one lancet relative to the other, two different air flow streams are generated so that within each corrugation 33, the downstream lancet 40 is not in the wake of the upstream lancet 38. Because the downstream lancet 40 is not in the wake of the upstream lancet 38, the downstream lancet 40 can create a turbulent flow within the air stream passing over it. That is, the fluid flow. { usually air) immediately adjacent to a lancet will not be adjacent to the next lancet downstream. Therefore, the leading edge of both, the upstream lance 38 and the downstream lance 40 see a velocity profile capable of initiating a new boundary layer (i.e., restarting the boundary layer) that will optimize the transfer thermal for both lancets 38, 40.
As modalized herein and shown in Figure 2B, the upstream lancet 38 is inclined to prevent flow adjacent the upstream lancet 38 to strike the downstream lancet 40. In a preferred embodiment, the downstream lancet 40 is horizontal, as shown in Figure 2B. The upstream lancet 38 is inclined at an angle alpha with respect to the mean air flow direction (left to right in Figure 2B) and the horizontal of the downstream lancet 40. The preferred alpha angle for tilting the upstream lancet 38 with respect to the average air flow direction varies between 5 and 15 degrees, with 11 degrees being the most preferred angle alpha. It is preferred that the downstream lance 40 be horizontal to the average air flow direction, so as to form an angle of approximately 0 degrees with respect to the average air flow direction. Alternatively, it is possible for the downstream lancet 40 to be inclined with respect to the upstream lancet 38 within the same angular scale, i.e. between 5 and 15 degrees. The lancets, however, should not be tilted at the same angle. By tilting one lancet relative to the other, two different air flow streams are generated so that the downstream lancet 40 is not in the wake of the upstream lancet 38, thereby maximizing the heat transfer for both lancets 38, 40 upstream and downstream. An example of a heat exchanger fin 130 designed in accordance with the present invention is shown in Figure 3. The measurements shown are in inches and are intended to be exemplary only. As shown in Figure 3, a fin 130 has a corrugated configuration comprising a plurality of corrugations. Each corrugation 133 includes a ridge and a trough forming a convexly rounded lance 142 and a concavely rounded lancet 144, respectively. As shown in Figure 3, each corrugation 133 includes an ascending ramp 134 and a descending ramp 136. Each ascending ramp 134 includes a lancet 138 and each descending ramp 136 includes a lancet 40. Each lancet 38 is inclined at an angle of approximately 11 degrees with respect to the average air flow direction and each lancet 40. Each lancet 40 is horizontal and parallel to the direction of medium air flow. As shown in Fig. 4, the air flow (illustrated as current lines) passes near / adjacent the inclined lancet 138 and is directed downwardly further, without impingement, the downstream crest 142 or lancet 140. horizontal before incising on the trough 144a. Similarly, the air flow passing adjacent the curved crest 142 passes over the horizontal lance 140 and trough 144a before impingement on the inclined lancet 138a downstream of the corrugation
133a. Additionally, the air is directed further, without impingement, the tundish 144a and the lancet 138a inclined downstream of the corrugation 133a. In this way, it can be seen that the flow adjacent to a certain lancet does not impinge on a lancet immediately downstream. In contrast, as shown in Figure 5, in conventional fins, the flow adjacent a given lancet impinges on a lancet immediately downstream. For example, the flow above a first horizontal lancet 239 impinges on the second horizontal lancet 241. In addition, the flow not immediately adjacent to the lancet 239 continues to remain above all the downstream lancets, preventing the mixing of the air layers and the restarting of the boundary layer. A method for manufacturing a fin having upstream lancets and downstream lancets is described below. The method includes applying a uniform increase to the fin material with a first die, cut the flap in a direction perpendicular to the average air flow with a second punch, and lift the lancets out of the uniform rise with the same second punch. As shown in Figure 2B, the flap 30 includes a uniform increase 32. The uniform increase 32 is produced by placing the fin material within a first die to form a corrugated configuration that is extruded from the material line. After the corrugated form is produced, the flap 30 is cut in a direction perpendicular to the average air flow with a second die. Two cuts are made to produce each lancet 38, 40. The lancets 38, 40 are formed of the corrugated form 32 that was extruded from the material line. Once the flap 30 is cut, the lancets 38, 40 are lifted out of the corrugated form 32 of the flap 30 by a punch. It can be the same die that cut the corrugated configuration 32 to form the lancets 38, 40. Alternatively, a different die can be used to define the lancets 38, 40 within the corrugated form 32. Raising the lancets 38, 40 outside the corrugated configuration 32 of the wing 30 includes positioning the downstream lancet 40 so that it will not be in the wake of the upstream lancet 38. In a preferred embodiment, this includes placing the downstream lancet 40 so that it is horizontal. In addition, the upstream lancet 38 is positioned so as to form an angle of between 5 and 15 degrees with respect to the direction of the average air flow. In a preferred embodiment wherein the downstream lancet 40 is horizontal, the upstream lancet 38 is also positioned so as to form an angle of between 5 and 15 degrees with respect to the downstream lancet 40. Preferably, the upstream lancet 38 is positioned to form an angle of 11 degrees with respect to the direction of the average air flow and the horizontal downstream lancet 40. Other embodiments of the invention will be apparent to those experienced in the field from a consideration of the specification and practice of the invention described herein. It is intended that the specification and examples be considered as examples only, with a true scope and spirit of the invention being indicated by the following claims.